“I have a patient with facial cellulitis but they’re not responding to antibiotics, my Consultant has asked me to find out if there is a stronger antibiotic we can give” said the oncall doctor.
 
The Microbiologist rolled his eyes; why do people persist in thinking about antibiotics in terms of “stronger” when what they really mean is “broader spectrum”!
 
“Why don’t you start by telling me something about the patient?” said the Microbiologist through gritted teeth.
 
“Oh, okay” said the Doctor, thinking this was just going to waste more of his precious time.
 
“She has just returned from trekking in Bolivia where they stayed in mud huts. The patient thinks they might have been bitten on the face as there were quite a lot of big beetles around. She now has a swollen right eye and we’ve been giving IV Teicoplanin but it hasn’t made any difference so we want to give her something… stronger.”
 
His curiosity piqued, the Microbiologist let the latest “stronger” slip past.
 
“Are both upper and lower eyelids swollen? What did the insects look like exactly?”

​“Yes, both eyelids are swollen and I have no idea what the bugs looked like” said the Doctor, thinking this was taking entirely too long.
 
“Okay, this sounds like Romana’s sign. I think your patient might actually have Chagas disease. Have you done a blood film? You need to send us blood for PCR and in the meantime I’ll pop over and see if your patient can describe the bugs in more detail”.
 
“Huh, so there is no antibiotic choice then?” grunted the Doctor thinking he wasn’t going to get that stronger antibiotic after all… and got the impression the Microbiologist was going off on a tangent which he wasn’t going to know much about!
 
What is Chagas disease?
Chagas disease, also known as American trypanosomiasis, is caused by the parasite Trypanosoma cruzi. Most mammals can be infected by T. cruzi including humans, rodents, cats, dogs and cattle.
 
Infection is spread by an insect vector, usually the Triatomine bugs (also known as Kissing, Reduviid or Assassin bugs). While the bug is feeding it defecates and leaves it’s faeces to either penetrate the bite wound or, if on the face, it penetrates through the conjunctiva… yep it poos in your eye! Gross….
 
Chagas disease can also be spread via blood transfusion from an infected donor as well as congenital infection from an infected mother to her child (the risk of congenital infection from an infected mother is up to 10%). Many countries have systems in place to restrict blood donation from those who have either lived in or visited endemic countries. Less commonly infection can occur from transplanted organs or via ingestion of food or water contaminated with Reduviid bug faeces.
 
Apparently Chagas disease is responsible for the most illnesses and deaths of any parasite in the Western hemisphere, including more than malaria! Chagas disease occurs throughout the Americas from the Southern United States to the North of Argentina and Chile, with an estimated 6 million cases. The highest prevalence of Chagas disease is in Bolivia, Argentina, Paraguay, Ecuador, El Salvador, and Guatemala.
 
Traditionally Chagas disease was an infection of people in rural areas where the insect vector lived in cracks in the walls, or the thatched roofs, of adobe houses. However with increasing population movement both internally and globally Chagas disease acquired rurally can present at a later date in urban environments as well as in non-endemic countries. Control programs have eliminated the insect vector in countries like Brazil meaning that the proportion of congenital infections is now higher than naturally acquired infection.
 
How does Chagas disease present?
The incubation period for Chagas disease is usually 1-2 weeks but can be up to 4 months in transfusion transmission.
 
Most acute infections (within 8-12 weeks) with T. cruzi occur in children and are asymptomatic or very mild. Others experience mild fever, lymphadenopathy, malaise and hepatosplenomegaly (enlarged liver and spleen). A few patients get a swelling at the site of inoculation, known as a Chagoma; if this occurs after conjunctival inoculation causing swelling of the eye lids then it is known as Romana’s sign. Serious acute infection with myocarditis or meningoencephalitis occurs in less than 1% of patients.
 
However the most serious manifestations of Chagas disease, in 20-40% of patients, present up to 30 years later with either cardiac or less commonly gastrointestinal disease.
 
Cardiac Chagas disease usually presents with progressive heart failure, shortness of breath, fatigue, pulmonary and peripheral oedema (fluid accumulation) and chest pain. The heart becomes dilated and there is a risk of arrhythmias and emboli as a result of the heart not beating properly. The prognosis from cardiac disease is poor with over 30% dying from sudden cardiac death within 8 years from diagnosis. Others will die young from progressive heart failure; although there are scoring systems, e.g. the Rassi score, for trying to work out who will die and when, these are not that reliable.
 
Gastrointestinal Chagas disease is due to an autoimmune cross reaction triggered by antibody against the parasite which damages the nerves supplying the gut, especially the oesophagus and distal colon. Loss of innervation leads to progressive dilatation and eventually mega-oesophagus and mega-colon. Patients are unable to swallow safely and are at risk of aspiration and choking; they also become unable to absorb food properly, develop bowel obstruction and malnutrition.
 
How is Chagas disease diagnosed?
The easiest way to diagnose acute Chagas disease is to look at a film of blood and see the parasite in the red blood cells. The parasitaemia lasts about 90 days; in chronic infections the film will be negative as the parasites have been cleared from the bloodstream. Acute Chagas disease is now normally diagnosed using PCR on whole blood.
 
Chronic Chagas disease is difficult to diagnose and requires demonstration of IgG against T. cruzi. Because none of the tests are particularly good, and are prone to false positives, two different tests based on different antibody reactions should be used and the diagnosis made if BOTH are positive AND the patient has evidence of myocarditis or gastrointestinal disease.
 
Patients treated for Chagas disease should have follow up serology; the IgG should reduce with successful treatment. If the amount of IgG does not reduce then the patient may require retreating.
 
How is Chagas disease treated?
There are 2 parts to the treatment of Chagas disease; treatment of the parasitic infection and treatment of the chronic cardiac and gastrointestinal complications.
 
Antiparasitic drugs are used for both acute and chronic Chagas disease. There are two drugs; Benznidazole and Nifurtimox. Benznidazole tends to be first line treatment as it is better tolerated with fewer side effects. Treatment in acute infection reduces the duration and severity of symptoms (if present) and clears the parasitaemia resulting in cure in 60-85% (>90% for congenital infection if treated in the first year of life).
 
Treatment with antiparasitic drugs in the chronic form can reduce progression of cardiac and gastrointestinal disease by about 70-80%, especially if given before symptoms have progressed too far towards severe heart failure, mega-oesophagus or mega-colon.
 
Cardiac disease is treated in the same way as heart failure or arrhythmias for other causes with diuretics, beta-blockers and anticoagulants. Gastrointestinal disease is managed with dietary changes but ultimately patients may require extensive surgery with oesophagectomy and colectomy.
 
Prevention
The best way for travellers to prevent infection with T. cruzi is to avoid being exposed to the insect vector, sleeping under insecticide impregnated nets, not staying in rustic accommodation and avoiding street food that might be contaminated with insect faeces. Essentially travellers can avoid infection by normal simple common sense “safe traveller” behaviour.
 
For people living in endemic countries the same measures for prevention apply. Many South American countries have embarked on programs to improve rural housing by replacing adobe huts with brick and corrugated iron buildings… not as pretty maybe but considerably safer.
 
Congenital infections can be reduced by screening pregnant women by PCR as negative PCR correlates with very low or absent parasites in blood and therefore substantially reduced risk of in utero infection. There are no drugs that can be used safely in pregnancy to reduce the risk of transmission in PCR positive women. You have to wait for the child to be born before trying to treat the child and the mother.
 
So the Microbiologist spoke to the patient who described the Reduviid bugs in great detail (apparently they are 2cm long but quite pretty!). A film was looked at that day by the haematologists who saw parasites in the blood film. With the diagnosis confirmed the patient was started on Benznidazole and follow up blood tests fortunately showed a complete cure, although they had developed a phobia to big creepy bugs… but I guess that was to be expected really!

Back in November last year I wrote a blog about tick borne encephalitis (TBE) in the UK caused by viruses under the title “Deadly brain disease passed by ticks now in Britain”… not my title but rather the Telegraph newspaper. This was related to the discovery of deer ticks in Thetford Forest which showed evidence of infection with the TBE Flaviviruses. However this isn’t the only cause of TBE in the World, there are others such as the parasitic disease babesiosis… and you’ve guessed it…. we now have it here in the UK! Wonderful!?

“I have a patient with a bright red nose” said the junior Doctor.
 
The Microbiologist double-checked his calendar to make sure it wasn’t March 15th and the junior performing a joke for Comic Relief’s “Red Nose Day”, a charity day here in the UK!
 
“What do you mean a bright red nose” the Microbiologist asked, adding “it’s not Comic Relief Day, you know?” heading off the “fooled you” prank.
 
“What!?”... The junior inhaled deeply, ignored the Microbiologist, and continued “It’s a kind of reddish purple and very painful. It looks a bit like cellulitis but it is in a very odd place, and the patient doesn’t have a fever. What antibiotics do you think we should give?”
 
Muttering, “this isn’t just a dial an antibiotic line”, the Microbiologist decided he would like to see this patient’s nose and find out what was going on himself before advising what treatment should be started…
 
He added “your patient needs a diagnosis before throwing random drugs at them to see if they get better”.
 
As the Microbiologist walked into the patient’s room to introduce himself he couldn’t help but see that the patient did indeed have a bright red nose. He chuckled to himself; the patient definitely didn’t need one of those plastic red noses.
 
After a brief embarrassed pause the Microbiologist finally introduced himself. The patient smiled and then unconsciously reached up and stroked his nose with his thumb and forefinger.
 
With sudden understanding the Microbiologist asked “do you have anything to do with animals, either work or at home?”
 
“I am a keen keeper of Koi carp and have just finished transferring them to their new pond… I designed it myself” the patient said proudly.
 
It was the Microbiologists turn to smile. “You have erysipeloid” he told the patient confidently.
 
“Eh, sip, what? No, I have Koi carp, they’re fish!” said the patient, confused.

I came across a story this week about a patient from Florida, USA, who had been diagnosed with a really unusual infection caused by a microorganism called Naegleria fowleri. It caught my attention because firstly it is very rare and so I was intrigued and secondly because during a lockdown it should be extremely difficult to catch it! So I had to investigate further…
 
What is Naegleria fowleri?
Naegleria fowleri is a free-living amoeba found in freshwater and soil throughout the World, preferring temperatures between 30-45 oC. It does not survive in seawater. The most common risk factor for acquiring N. fowleri is contact with water through sports such as swimming, water skiing and diving as well as messing around in mud or bathing in contaminated hot springs (it is “free-living” after all!). So this explains my curiosity as to how this patient had acquired their infection as it should be very difficult to “get exposed” to N. fowleri during a lockdown, because there wouldn’t be any water sports or other exposures going on at this time!

“What antibiotics should we start for Nipah Virus?” asked the newly qualified Doctor.
 
The Microbiologist nearly fell off his chair.
 
“What?! Nipah Virus? Who the heck do you think has Nipah Virus?” exclaimed the Microbiologist.
 
“I have a patient with a headache and confusion and I’ve been reading about the causes of encephalitis and want to treat them in case it is Nipah Virus” the Doctor replied.
 
The Microbiologist muttered to himself… the only one confused here was surely this Doctor… why did this always happen on a Friday… I’m the only one with a headache…
 
“Has the patient travelled? Have they had any contact with animals? Have they been in contact with anyone else unwell?” asked the Microbiologist.
 
“Well no, but Nipah Virus can cause encephalitis so we should rule it out at least” said the Doctor defensively.
 
The Microbiologist sighed, “let me tell you a bit about Nipah virus….”

SARS Coronavirus 2 (SARS Cov2), the cause of the infection Covid-19, is a zoonotic infection; it has been transmitted from an animal to a human. Genetic analysis of the virus has shown that SARS Cov2 is an intestinal bat coronavirus that has successfully made the jump from bats to humans, probably as a result of human contact with bat guano.
 
Although that sounds alarming, zoonotic infections are actually quite common and have been a problem for Homo sapiens/humans ever since we crawled out of the primordial slime millions of years ago.

One of my biggest concerns around the current Covid-19 pandemic is that all of the normal things that make people sick haven’t gone away. This concerns me because whilst Covid-19 is on the minds of healthcare staff they may inadvertently delay considering all of the other clinical problems that will continue to be going on in the background. Patients will still be coming in with appendicitis, UTIs, heart attacks and strokes; in fact ANY acute medical or surgical problem that happens in a normal day in the NHS.

“We have a patient with an odd infection of the face and neck and want to know what antibiotics to start” said the ENT Doctor.
 
“What do you mean by odd?” asked the Microbiologist vaguely, distracted by all of the requests for coronavirus testing that where sitting in the laboratory.
 
“Well the patient has bilateral swelling of her face and neck and difficulty swallowing, and it’s a bit odd to be bilateral”.
 
The Microbiologist perked up and started to pay more attention.
 
“What does she do? Has she injured herself recently? Does she have pain on opening her mouth? What’s her vaccination history?” he asked.
 
“Errrr. She’s retired. We haven’t asked about injuries. She can’t open her mouth. She’s 77 years old so we haven’t asked about vaccines” answered the ENT Doctor.
 
“Okay. Go and ask her the questions. More specifically is she a keen gardener? Has she had any injuries, however minor, which might have been contaminated with soil or manure? When did she last have a tetanus immunisation? I’ll stay on the phone while you ask. This sounds like it might be tetanus”.
 
There was a pause, then the sound of the phone being put down on the desk, whilst the ENT Doctor went off to get some answers…
 
The Microbiologist tapped his desk nervously, “see, see not all patients are presenting with Covid-19, and I do wonder how many “ordinary” illnesses are being overlooked amongst the Covid-19 shenanigans…”
 
The ENT Doctor returned to the phone and asked … “are you still talking to me?”
 
“Oh umm, no I’m just ranting a little to myself” replied the Microbiologist.

“We have a lady with puerperal fever. She’s 2 days post-delivery and pretty unwell. Critical Care are reviewing her now and we’d like some advice about the best antibiotics to give her” said the Obstetrics Registrar.
 
Excellent thought the Microbiologist; they’re being proactive about a serious problem.
 
“If she’s not allergic to anything then IV Benzylpeniciilin and Clindamycin. Have you looked for retained products and done a DNC?” asked the Microbiologist.
 
“She’s really unwell, we don’t really want to take her to theatre. We might damage the uterus” replied the Registrar.
 
“She’s unlikely to improve if you don’t,” said the Microbiologist sympathetically. “You need to remove as much infected material as you can. I know it sounds brutal but it’s really important”.
 
“Okay,” said the Registrar sounding doubtful, “my Consultant is with the patient at the moment so I’ll go and tell them what you have advised. Thanks for your help.”
 
The Microbiologist put down the phone and put down his pen. Time to visit the obstetric ward and see what is going on…

It’s all over the news; a new deadly plague is spreading across the World in an unstoppable wave of death and disease! Cities are falling, governments are collapsing, mass panic and chaos are ensuing… or at least that’s what the media would have us believe about the novel coronavirus from Wuhan in China. Gosh, it’s reminding me of the game of Pandemic!